Lasersaber strikes again. A joule thief king ?

[TinselKoala]

I've found that the MPSA18 and the BC337-25 are similar but in some circuits one works better and in others, the other one. Lately I build everything with sockets or easy solder pads so I can do easy comparisons without changing much else in a circuit.

[d3x0r]

I don't know how many of you are youtube addicts...


https://www.youtube.com/watch?v=s3T6kEic5G0


Not just a glimmer of light.

[d3x0r]

I had 2 NTE47's, but ended up overpowering both... so while I was looking for a replacement I noticed some details.


NTE47 Vbe On = 0.7   (100Mhz)  Hfe 400-1150
MPSA18 Vbe On = 0.65 (something) (100Mhz)  Hfe 400-1500


Which is a lower base-emitter voltage drop than anything else I have... many are 1.2+


Germanium transistors (they say) can have a Vbeo  of 0.15V  (fanstastic!)  but the gains on the germanium transistors I see are only 100-200.....




And Germanium transistors have a 'cutoff frequency?'  They are actually really slow like between 2-10Khz ?

[conradelektro]

I made some scope shots from the MPSA18 circuit of Lasersaber as depicted here http://laserhacker.com/?p=410

The MPSA18 has a very short on-time (about 600 nS) and this is the reason for the low power draw. My replication draws less than 0.3 µA (but the red LED is very dim).

see also: http://www.overunity.com/14591/lasersaber-strikes-again-a-joule-thief-king/msg405172/#msg405172

In Lasersaber's latest video (no circuit drawing available yet) https://www.youtube.com/watch?v=s3T6kEic5G0 the LEDs are much brighter. But as far as I understand the power draw is several hundred µA.

Greetings, Conrad

[d3x0r]

I made some scope shots from the MPSA18 circuit of Lasersaber as depicted here http://laserhacker.com/?p=410

The MPSA18 has a very short on-time (about 600 nS) and this is the reason for the low power draw. My replication draws less than 0.3 µA (but the red LED is very dim).

see also: http://www.overunity.com/14591/lasersaber-strikes-again-a-joule-thief-king/msg405172/#msg405172

In Lasersaber's latest video (no circuit drawing available yet) https://www.youtube.com/watch?v=s3T6kEic5G0 the LEDs are much brighter. But as far as I understand the power draw is several hundred µA.

Greetings, Conrad

Ya; but before I blew up my NTE47's I had a hand-crank lantern, and attaching it to a 3300uF cap takes only a few turns to charge to 9 volts....


Daniel Nune'z hand crank demonstration...
https://www.youtube.com/watch?v=Z4mTA794U4E  (for instance) I think he's using a similar driver....  no idea how big his cap is...


Oh; but ya  mine only runs for seconds... using the oroiginal lighs from the lantern; which IS longer than they run directly on the generator....